Senior Performance Software Engineer
at Mozilla Corporation
Core Product-Firefox
Remote UK, Remote US, Remote Canada, Remote Germany, Remote France

Why Mozilla?

Mozilla Corporation is the non-profit-backed technology company behind pioneering brands like Firefox, the privacy-minded web browser, and Pocket, the content discovery platform. More than 270 million people around the world use its products each month.

Along with 20,000+ volunteer contributors and collaborators all over the world, Mozilla Corporation’s staff are driven by our vision to be the trusted guide through a joyful internet. We design, build and distribute software that enables people to enjoy the internet on their terms.

The Opportunity

At Mozilla, we believe that the web should be responsive, pages should load quickly, and resources should be used thoughtfully. The performance program is dedicated to building performance for every experience, growing a culture of performance, and to bring a balance between what is good for the users of the web and what is good for the builders of the web.

Our team is geographically-distributed, and working in the open is the norm. We contribute to the code driving the Firefox browser on a number of platforms - Windows, Android, Linux, and macOS. Our focus is on finding and fixing things that slow down the browser as well as helping other teams write fast and reliable code to make Firefox excellent for users.

As a senior systems engineer in performance, you will be responsible for low-level programming of the Firefox Profiler and other tools. Your focus will be on delivering an effective toolset for Firefox developers looking to track down and seize every opportunity to improve the quality of experience for our users. You will work closely with performance experts to identify and surface the most valuable measurements across a variety of platforms.

What you’ll do 

  • Support, maintain, and develop features for the Firefox Profiler (C++) project.

  • Engage with the Performance team efforts such as bug triage and strategy.

  • Develop performance tooling projects to support the Gecko platform.

  • Engage with other Firefox engineers to help them learn how to use our tools efficiently, and find opportunities to make our tools serve them better.

  • Promote and encourage use of the performance tools through outreach.

  • Mentor and engage with volunteers contributing to the codebase.

What you’ll bring 

  • Excellence in modern programming (C/C++). Familiarity with Rust would be a bonus.

  • Background in low-level software and operating systems, with expertise in at least one of Windows/Linux/macOS and familiarity with the others.

  • Experience working on and debugging large multi-threaded applications and memory management.

  • Knowledge of profiling, performance tooling, and testing.

  • Knowledge of Python, JavaScript, and other web technologies is desirable.

  • Knowledge of Java or experience with Android development is a plus.

About Mozilla 

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and controlled. When you work at Mozilla, you give yourself a chance to make a difference in the lives of Web users everywhere. And you give us a chance to make a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online.

Commitment to diversity, equity, inclusion, and belonging

Mozilla understands that valuing diverse creative practices and forms of knowledge are crucial to and enrich the company’s core mission.  We encourage applications from everyone, including members of all equity-seeking communities, such as (but certainly not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of all sexual orientations, gender identities, and expressions.

We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at to request accommodation.

We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national origin, pregnancy, ancestry, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws.  Mozilla will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose.

Group: C


Req ID: R2008

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Why Mozilla?

At Mozilla, we’re serving humanity—by maintaining a safe, open internet—while also helping the individual humans employed here to reach their personal and professional goals. With a relatively small team serving hundreds of millions of people, a culture of exploration, and a commitment to mentorship, opportunities abound to learn and grow at Mozilla.

Our values drive our actions

  • Purpose is built into our work, with our mission driving every decision
  • We challenge assumptions, the status quo, ourselves, and each other
  • We are transparent: in our code, our business partnerships, and our everyday interactions
  • We seek out people from diverse backgrounds and with perspectives different from our own
  • We pair purpose with performance and put people ahead of profit

Our impact is global

  • 700+ paid staff from over 30 countries
  • Thousands of volunteer contributors across six continents
  • 5 global offices: San Francisco, Toronto, Paris, Berlin, and Beijing
  • Hundreds of home offices globally

Our benefits are world-class

  • Flexible work environment (nearly half of Mozillians work remotely)
  • Industry-leading paid parental leave (up to 26 weeks of fully paid leave for childbearing parents and up to 12 weeks for non-childbearing parents)
  • Reimbursement for professional development (up to $3,000/year)
  • A work setup including the latest hardware and software of your choice